Hello!
Let's talk about restrictive lung diseases today.
We know that an increased FEV1 / FVC ratio is suggestive of a restrictive lung disease.
However, you want to get lung volumes and confirm it by looking at the reduced TLC.
There are two types of restrictive lung diseases that you want to differentiate - pulmonary and extrapulmonary.
In pulmonary restrictive lung disease, all lung volumes are reduced due to fibrosis.
In extrapulmonary restrictive lung disease, the residual volume will be normal or even increased.
Why? Because in neuromuscular diseases, the muscles don't have the strength to blow air out.
DLCO is another way you can differentiate the two.
In pulmonary restrictive lung disease, the surface of alveolar membrane that participates in gas exchange is reduced and the DLCO is low.
In extrapulmonary restrictive lung disease, the DLCO is normal.
That's all!
-IkaN
Nice
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